The present invention relates to an apparatus for processing substrates in a fluid tank, with at least one fluid inlet opening and at least one overflow opening in the upper region of at least one side wall of the fluid tank, wherein the opening area of the overflow opening is changeable.
An apparatus of this type is known from printed documents U.S. Pat. No. 5,275,184, U.S. Pat. No. 5,282,923, JP 3-233930 A2, U.S. Pat. No. 5,381,808, JP 5-94978 A2, JP 5-36666 A2, JP 6-53205 A2, JP 3-20031 or DE-A-44 13 077 filed by the instant applicant. The fluid that is introduced via the fluid inlet openings flows over the upper edge of at least one side wall of the fluid tank. These known apparatus do not make it possible to vary the fluid discharge as a function of existing conditions or of the type of fluid used, i.e. liquids or gases.
From U.S. Pat. No. 5,071,488 an apparatus of the aforementioned type is known in which the side wall of the fluid tank has an overflow edge and a knife edge arranged opposite the overflow edge so that a capillary action results in the gap between the overflow edge and the knife edge that causes removal of fluid form the fluid container. The width of this gap can be adjusted by adjusting a bolt.
It is an object of the present invention to provide an apparatus of the aforementioned type with which a gas provided for performing the drying process is used as efficiently and economically as possible during the drying process.